Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

[caphair]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

When the power MOSFETs are removed, then there will no longer be any heavy load to cause the TH1 to blow like that, shorted bridge will be the one or shorted Caps.
The Gate drive outputs will be switching ON and OFF at high frequency not steady DC.

Does a meter pick up that switching in dcv setting or no?

[budm]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

The frequency output can be up to 100KHz (per diagram it shows 40KHz) so I doubt that the DC reading from your meter will show correct reading, you need scope to look at the signal, or in AC mode if your meter still does not have high enough bandwidth, scope will be the correct way.
If you will just put in the new MOSFET, you will have high chance of bowing up the new MOSFET if the outputs are not switching (those two outputs are not turned in phase otherwise both MOSFETs will be on at the same time and will be big blow up), I do not think you will want to blow up the new MOSFETs, I wouldn't.

You can try checking the internal MOSFETs of the IC (test it off the board) to see if they are shorted out, it is not 100% because it could have blown open circuit due to the power supply Voltage (~320VDC) dumped into the output pins.

[caphair]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

My meter has frequency function and it only read frequency on one gate of one MOSFET as I mentioned in previous post. Same one read 5vdc also. I wasn't sure if that was normal and it was measuring quick pulses of 5v on signal?

[budm]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

At this point to I would just get new IC unless you have the scope to look for proper signals.

[caphair]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

I've ordered a new ic. In the meantime I've tested the two main filter caps in circuit and got a farad reading of them both added together. Does this conclude they're not shorted or I need to desolder and test individually?

[caphair]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

Put in new mosfets, ic, and fuse keeps blowing. Almost instantly. I don't know what else to do? I've checked pretty much everything in the smps primary except for the daughter board because there's glue still that's tough to get off without possibility of breaking little components on it

[caphair]

Re: Klipsch Pro Media 2.1 Speakers - Keep blowing mosfets

Any idea?